US10875770B2 - Method and equipment for cooling sulphuric acid - Google Patents

Method and equipment for cooling sulphuric acid Download PDF

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US10875770B2
US10875770B2 US16/078,168 US201616078168A US10875770B2 US 10875770 B2 US10875770 B2 US 10875770B2 US 201616078168 A US201616078168 A US 201616078168A US 10875770 B2 US10875770 B2 US 10875770B2
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acid
sulfuric acid
heat exchanger
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water
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US20190202694A1 (en
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Nelson Perella Clark
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NC Engenharia Industria e Comercio Ltda
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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B17/00—Sulfur; Compounds thereof
    • C01B17/69—Sulfur trioxide; Sulfuric acid
    • C01B17/74—Preparation
    • C01B17/76—Preparation by contact processes
    • C01B17/80—Apparatus
    • C01B17/806—Absorbers; Heat exchangers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/46—Removing components of defined structure
    • B01D53/48—Sulfur compounds
    • B01D53/50—Sulfur oxides
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B17/00—Sulfur; Compounds thereof
    • C01B17/69—Sulfur trioxide; Sulfuric acid
    • C01B17/74—Preparation
    • C01B17/76—Preparation by contact processes
    • C01B17/765—Multi-stage SO3-conversion
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B17/00—Sulfur; Compounds thereof
    • C01B17/69—Sulfur trioxide; Sulfuric acid
    • C01B17/74—Preparation
    • C01B17/76—Preparation by contact processes
    • C01B17/80—Apparatus
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
    • F28D1/00—Heat-exchange apparatus having stationary conduit assemblies for one heat-exchange medium only, the media being in contact with different sides of the conduit wall, in which the other heat-exchange medium is a large body of fluid, e.g. domestic or motor car radiators
    • F28D1/02—Heat-exchange apparatus having stationary conduit assemblies for one heat-exchange medium only, the media being in contact with different sides of the conduit wall, in which the other heat-exchange medium is a large body of fluid, e.g. domestic or motor car radiators with heat-exchange conduits immersed in the body of fluid
    • F28D1/0226—Heat-exchange apparatus having stationary conduit assemblies for one heat-exchange medium only, the media being in contact with different sides of the conduit wall, in which the other heat-exchange medium is a large body of fluid, e.g. domestic or motor car radiators with heat-exchange conduits immersed in the body of fluid with an intermediate heat-transfer medium, e.g. thermosiphon radiators
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
    • F28D1/00—Heat-exchange apparatus having stationary conduit assemblies for one heat-exchange medium only, the media being in contact with different sides of the conduit wall, in which the other heat-exchange medium is a large body of fluid, e.g. domestic or motor car radiators
    • F28D1/02—Heat-exchange apparatus having stationary conduit assemblies for one heat-exchange medium only, the media being in contact with different sides of the conduit wall, in which the other heat-exchange medium is a large body of fluid, e.g. domestic or motor car radiators with heat-exchange conduits immersed in the body of fluid
    • F28D1/03—Heat-exchange apparatus having stationary conduit assemblies for one heat-exchange medium only, the media being in contact with different sides of the conduit wall, in which the other heat-exchange medium is a large body of fluid, e.g. domestic or motor car radiators with heat-exchange conduits immersed in the body of fluid with plate-like or laminated conduits
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
    • F28D21/00—Heat-exchange apparatus not covered by any of the groups F28D1/00 - F28D20/00
    • F28D2021/0019—Other heat exchangers for particular applications; Heat exchange systems not otherwise provided for
    • F28D2021/0022—Other heat exchangers for particular applications; Heat exchange systems not otherwise provided for for chemical reactors
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/10—Process efficiency
    • Y02P20/124—
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/10—Process efficiency
    • Y02P20/129—Energy recovery, e.g. by cogeneration, H2recovery or pressure recovery turbines
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/50—Improvements relating to the production of bulk chemicals
    • Y02P20/57—

Definitions

  • This specification relates to an application for patent of invention for a method and equipment for cooling aqueous sulfuric acid solutions belonging to the field of chemical processes, which have been developed to provide more safety when cooling acid, for applications in processes with and without energy recovery and providing multiple embodiments to fit different plants for the manufacture of sulfuric acid by contact process.
  • One of the stages of sulfuric acid (H 2 SO 4 ) production by contact process is the absorption of SO 3 (sulfur trioxide) obtained by means of a stream of concentrated aqueous sulfuric acid solutions (sulfuric acid) in a column or liquid gas contact device such that the product from such reaction is an more concentrated sulfuric acid, which will be later diluted in concentrations for use in a process and/or for sale purposes.
  • SO 3 sulfur trioxide
  • This reaction is highly exothermic and releases a substantial amount of energy, which concentrates and heats the acid stream used in the absorption/reaction process such that the even more concentrated acid stream exiting the process is also hotter.
  • This energy (heating) needs to be removed from the system in order to keep the process parameters under control, and so that the absorption takes place within the designed and desired temperature and concentration ranges.
  • Another object is to provide a method and equipment for cooling sulfuric acid, which are flexible to provide several application variants.
  • Another object is to provide a method and equipment for cooling sulfuric acid, which are flexible to be applied to acid manufacturing processes with no energy recovery or acid manufacturing processes with energy recovery for application in the acid manufacturing process or other adjacent processes or also in the generation of electric power or other means of energy recovery.
  • Another objective is to provide a method and equipment for cooling sulfuric acid, which reduce or minimize the risk of corrosion of the equipment and materials in case of a leak, and thus reduce or minimize the risk of hydrogen formation and its consequences.
  • the method and equipment for cooling sulfuric acid object of this patent have been designed to comprise, instead of cooling the hot sulfuric acid effluent from the absorption reactions with water, as usually happens, cooling it down with coolants that are inert to sulfuric acid, such as perfluorocarbons fluids, C5-C29 chain fluorinated fluorohydrocarbons, such as, for example, hydrofluoroethers or perfluoropolyethers or mixtures thereof, such that in a first step, the sulfuric acid is cooled by indirectly transferring heat to this fluid and in a second step, such fluid indirectly exchanges heat with the water or any other coolant, is cooled and reused, wherein such method can be used for simply cooling sulfuric acid, or additionally for producing low, medium or high pressure steam or for heating other process streams, whether from the acid manufacturing plant or adjacent industrial plants or processes.
  • coolants that are inert to sulfuric acid, such as perfluorocarbons fluids, C5-C29 chain fluorinated fluorohydrocarbons,
  • FIGURES ILLUSTRATING THE INVENTION
  • FIG. 1 shows a scheme of a conventional indirect sulfuric acid cooling system without energy recovery, steam generation
  • FIG. 2 shows a scheme of indirect sulfuric acid cooling system without energy recovery, steam generation, according to this invention, which uses an inert coolant and intermediate acid-fluid heat exchanger;
  • FIG. 3 shows a scheme of a conventional indirect sulfuric acid cooling system with energy recovery, steam generation
  • FIG. 4 shows a scheme of a conventional redundant sulfuric acid cooling system with energy recovery, steam generation
  • FIG. 5 shows a scheme of one embodiment of the indirect sulfuric acid cooling system with energy recovery, steam generation, which uses an inert coolant, intermediate heat exchanger and boiler, according to the invention with plate heat exchangers and
  • FIG. 5 A shows one embodiment with shell and tube exchangers;
  • FIG. 6 shows a scheme of one embodiment of the indirect sulfuric acid cooling system with energy recovery, steam generation, according to this invention
  • FIG. 7 shows a system with an intermediate heat exchanger that heats more than one user, according to the invention.
  • FIG. 8 shows a system with an intermediate heat exchanger that heats more than one user with approximate values for a sulfuric acid production plant with an approximate capacity of 1000 t/day, according to the invention with a plate heat exchanger and FIG. 8 A shows one embodiment with a plate, and a shell and tube heat exchanger; and
  • FIGS. 9-11 schematically show choices of heat exchangers, i.e. plate, shell and tube and spiral, respectively, used in the equipment of the invention for cooling both the coolant and the acid.
  • the method and equipment object of this patent are part of the contact process for production of sulfuric acid (H 2 SO 4 ) with or without energy recovery.
  • said contact process for the production of sulfuric acid without energy recovery typically comprises the following steps among others ( FIG. 1 ):
  • Step 3 energy recovery, steam generation for use in the process for manufacturing sulfuric acid or in other adjacent processes or electric power generation or others.
  • FIGS. 2, 5-8 The method and equipment of this invention ( FIGS. 2, 5-8 ) are intended to cool sulfuric acid with shell and tube, plate or spiral type heat exchangers or the like, with or without energy recovery, in order to overcome the drawbacks of the prior art.
  • step 2 Indirect cooling, according to the method of the present invention, instead of using cooling water as usually occurs, uses fluids such as perfluorocarbons or fluorinated hydrocarbons with chains of 5 or more carbon atoms, such as for example hydrofluoroethers or perfluoropolyethers or mixtures thereof or the like.
  • fluids such as perfluorocarbons or fluorinated hydrocarbons with chains of 5 or more carbon atoms, such as for example hydrofluoroethers or perfluoropolyethers or mixtures thereof or the like.
  • the choice of the most suitable fluorinated fluid is mainly subject to the hot acid temperatures, once shorter chains have more favorable yet more volatile heat transfer characteristics while longer chains are less effective but less volatile in terms of heat transfer.
  • Step 2—indirect cooling according to the present invention comprises:
  • steam generation it further comprises step 3)—Energy recovery, steam generation, which generates heated water/steam that may be used in the process for manufacturing sulfuric acid or in other adjacent processes or in the generation of electric power or others.
  • a SO 3 absorption tower 1 ( FIG. 1 ), its outlet 2 through which the heated concentrated sulfuric acid effluent circulates; the concentrated sulfuric acid circulation tank 3 and pump 4 .
  • FIG. 1 In case of a sulfuric acid manufacturing process of the non-energy recovery type, ( FIG. 1 ), ( FIG. 1 ), its outlet 2 through which the heated concentrated sulfuric acid effluent circulates; the concentrated sulfuric acid circulation tank 3 and pump 4 .
  • an acid cooling loop 10 comprising an acid-water heat exchanger 11 of the type using cooling water, which indirectly exchanges heat with the heated concentrated acid from the SO 3 absorption tower 1 ; a feeding tube 12 deriving from pump 4 , and which feeds sulfuric acid to the heat exchanger 11 ; a sulfuric acid recirculation tubing 13 at a concentration of 97.0 to 99.5% and a temperature of 70 to 90° C. for the SO 3 absorption tower 1 ; return and water supply tubing 14 to the heat exchanger 11 , among others.
  • concentrated sulfuric acid is corrosive and a corrosion process able to put it in contact with water, whether due to corrosion of metal materials or production flaws, will produce hot diluted sulfuric acid, i.e. even more corrosive than the concentrated acid.
  • This corrosion may damage or destroy the equipment and tubings among others, lead the plant to a downtime for hours or even days, and further lead to the generation of hydrogen, which in turn can cause an explosion.
  • the above-mentioned method object of the present invention (which uses a coolant inert to sulfuric acid; an intermediate step for cooling the heated acid-coolant; a second step for cooling the heated coolant-water/other fluid) has been designed, wherein, when a non-energy recovery process is performed by a device as shown in FIG. 2 , which uses an inert coolant and an acid cooling loop 10 provided with an intermediate heat exchanger, said exchanger can be a plate, shell and tube, spiral heat exchanger or another type of indirect contact, acid-coolant heat exchanger.
  • the acid cooling loop 10 ( FIG. 2 ) comprises an intermediate acid-fluid (plates, shell and tubes, spiral or another) heat exchanger 20 , which cools the heated concentrated sulfuric acid by thermal exchange with the inert coolant; a second fluid-water heat exchanger 11 , which receives and cools the inert heated coolant by thermal exchange with cooling water; a feeding tube 12 , which establishes a fluid connection between the pump 4 and the heat exchanger 20 , and feeds said sulfuric acid at a temperature of 70 to 120° C. and a concentration of 98 to 101% after absorption of SO 3 in the absorption tower 1 ; cooled sulfuric acid recirculation tubing 13 at a temperature of 70 to 120° C.
  • an intermediate acid-fluid (plates, shell and tubes, spiral or another) heat exchanger 20 which cools the heated concentrated sulfuric acid by thermal exchange with the inert coolant
  • a second fluid-water heat exchanger 11 which receives and cools the inert heated coolant by thermal exchange with
  • tubing 21 for reuse of the inert coolant which establishes a fluid connection between the intermediate acid-fluid heat exchanger 20 and the second fluid-water/other fluid heat exchanger 11 , and substantially comprising a tubing, an accumulation vessel and a recirculation pump; return and water supply tubing 14 for a second fluid-water heat exchanger 11 among others.
  • the leakage does not self-catalyze the corrosion of the equipment, it reduces the damage caused to it, reducing the cost of maintenance while extending the life of the equipment.
  • the system that uses a coolant either reduces the risk of a leakage in a plate heat exchanger or prevents it from destroying the heat exchanger because there is no water for diluting the acid, and thus it catalyzes its corrosiveness, avoiding the equipment destruction.
  • units featuring plate heat exchangers and spiral heat exchangers have an additional benefit when used with an intermediate loop with inert coolant compared to the plate or spiral heat exchangers set up in conventional systems.
  • the acid used for absorption in such units can be at temperatures varying from 100 to 240° C. and a concentration that may vary from 97% to 101%.
  • the acid cooling in this type of system instead of being made with acid-water heat exchangers, is made in boilers. As the hot acid cools down, the boilers produce low or medium pressure water steam, depending on the temperature of the acid used to absorb SO 3 and that is being cooled.
  • One of the first systems for recovering the energy produced during absorption of the hot acid has been designed by Monsanto Enviro-Chem Systems Inc. (U.S. Pat. Nos. 4,576,813, 4,670,242, 4,996,038, 8,586,001, WIPO Patent Application WO/2014/144699).
  • a typical unit of this kind comprises: ( FIG. 3 ) a single or double stage absorption tower assembly 1 , which absorbs SO 3 from the gases of the process with sulfuric acid at concentrations of 98-101% and temperatures above 120° C.; an acid outlet 2 after absorption, through which the heated acid circulates at a temperature between 120 and 240° C.; an acid circulation tank 3 and pump 4 .
  • the unit further comprises a cooling and energy recovery, steam generation loop 10 , comprising a steam generation boiler 30 that cools the acid and produces low or medium pressure steam; a feeding tube 12 , which establishes a fluid connection between the pump 4 and the boiler 30 through which the heated acid circulates after absorption at a temperature between 120 and 240° C., and a concentration between 97 and 101%; recirculation tubing 13 that connects the boiler outlet 30 to the SO 3 absorption tower 1 , through which the cooled acid circulates at a temperature between 100 and 240° C., and a concentration between 97 and 101%; water supply tubing 14 in the boiler at a pressure between 300 to 3000 kPa; tubing 31 for the escape of low or medium pressure (300 to 1500 kPa) from the boiler 30 .
  • a cooling and energy recovery, steam generation loop 10 comprising a steam generation boiler 30 that cools the acid and produces low or medium pressure steam; a feeding tube 12 , which establishes a fluid connection between the pump 4 and the
  • the plant further provides a cold acid feeding tube 15 for temperature adjustment in tower 1 , which feeds acid at a concentration between 97 and 101% and a temperature between 70 and 120° C.
  • All components of the system, tower, boiler, tanks, tubings are typically built from (noble) metal material specially selected to resist corrosion in sulfuric acid medium under the operating conditions.
  • the main drawback of this system is the risk of corrosion and downtime of the unit, particularly in case of a failure of the boiler 30 .
  • the saturated water/steam can come in contact with the acid, and precisely because they are pressurized, they may cause a very fast dilution of the acid—at a much higher speed than that at which it would occur should the fluids be at a closer pressure—with the consequent accelerated increase in temperature.
  • the diluted acid produced is extremely corrosive, is at a very high temperature and may destroy the entire system in just a few hours.
  • Such system leakage can be catastrophic if not repaired in a few minutes or hours.
  • a failure of this nature in the boiler will withdraw the entire unit from service, since the plant cannot be operated in another way unless with energy recovery.
  • a separated vessel 40 (typically a venturi scrubber) mounted upstream the SO 3 absorption tower 1 , which in turn operates by absorbing SO 3 eventually not absorbed in the first vessel using acid at the usual process temperatures in a range of 70-120° C., and concentrations about 97-99.5%, wherein such solution includes an acid cooling loop 10 comprising an acid-water heat exchanger 11 associated with the outlet of the SO 3 absorption tower 1 and a steam cooling and generation loop 10 ′ comprising an acid-water steam generation boiler 30 associated with the outlet of the vessel 40 .
  • an acid cooling loop 10 comprising an acid-water heat exchanger 11 associated with the outlet of the SO 3 absorption tower 1
  • a steam cooling and generation loop 10 ′ comprising an acid-water steam generation boiler 30 associated with the outlet of the vessel 40 .
  • the advantage of this system is that in the event of a failure in the boiler 30 , the absorption tower loop 1 can typically perform the entire absorption of SO 3 , preventing the plant from stopping due to a failure in the generation circulation and energy recovery system.
  • the key objective of the plant, i.e. to produce acid, is thus preserved in case of a failure of the energy recovery/steam generation system.
  • FIG. 4 An exemplary embodiment of this option is shown in FIG. 4 .
  • the equipment substantially comprises an absorption tower assembly consisting of SO 3 absorption tower 1 ; tower outlet 2 for the heated acid after absorption at 70 to 120° C.; acid circulation tank 3 and pump 4 ; additionally, said equipment comprises a SO 3 absorption vessel assembly connected upstream with the SO 3 absorption tower 1 comprising SO 3 absorption equipment (venturi scrubber), connection thereof 41 with the tower 1 , outlet 42 of the vessel through which the heated acid circulates after absorption at a concentration of 98% to 101% and temperature of 100 to 240° C.; acid circulation tank 43 and pump 44 .
  • SO 3 absorption vessel assembly connected upstream with the SO 3 absorption tower 1 comprising SO 3 absorption equipment (venturi scrubber), connection thereof 41 with the tower 1 , outlet 42 of the vessel through which the heated acid circulates after absorption at a concentration of 98% to 101% and temperature of 100 to 240° C.; acid circulation tank 43 and pump 44 .
  • the equipment further comprises an acid-water cooling loop 10 associated with tower 1 consisting of an acid-water heat exchanger 11 ; acid feed tubing 12 that connects the heat exchanger 11 with the pump 4 ; recirculation tubing 13 that connects the heat exchanger 11 with the tower 1 , through which the cooled acid circulates for absorption at a concentration of 97 to 99.5%, and temperature between 70 and 120° C.; and the cooling water supply and return tubing 14 from the heat exchanger 11 .
  • an acid-water cooling loop 10 associated with tower 1 consisting of an acid-water heat exchanger 11 ; acid feed tubing 12 that connects the heat exchanger 11 with the pump 4 ; recirculation tubing 13 that connects the heat exchanger 11 with the tower 1 , through which the cooled acid circulates for absorption at a concentration of 97 to 99.5%, and temperature between 70 and 120° C.; and the cooling water supply and return tubing 14 from the heat exchanger 11 .
  • Said equipment further comprises a cooling and energy recovery loop 10 ′ associated with the vessel 40 , and consisting of a steam generation boiler 30 ; tubing 12 ′ for connecting the pump 44 with the boiler 30 through which the acid circulates after absorption at a temperature between 100 and 240° C.; the acid recirculation tubing 13 ′ between the boiler 30 and the vessel 40 , through which the cooled acid circulates after steam generation between 100 and 240° C.; tubing 14 ′ for supplying water to the boiler at a pressure between 300 to 3000 kPa; the boiler steam outlet tubing 31 through which the low or medium pressure, 300 to 3000 kPa, steam circulates and that may be associated, for example, with an electricity generation turbine (not shown) or other.
  • a cooling and energy recovery loop 10 ′ associated with the vessel 40 , and consisting of a steam generation boiler 30 ; tubing 12 ′ for connecting the pump 44 with the boiler 30 through which the acid circulates after absorption at a temperature between 100 and 240° C.; the acid
  • a conventional energy recovery unit typically cools, for example, sulfuric acid at a concentration of 99.5% and temperature of 220° C. until, for example, a temperature of 200° C.
  • the pressures of the steam generated in the boiler of this system do not exceed 1000-1200 kPa at a saturation temperature of 170-180° C., therefore, 40° C. below the temperature of the hottest acid and 20° C. below that of the coolest acid.
  • FIGS. 3, 4 The above-described two examples of conventional sulfuric acid cooling systems with energy recovery ( FIGS. 3, 4 ) have an acid-water interface that causes the problems already discussed herein.
  • the method and equipment object of the present patent also have constructions to cool sulfuric acid and recover energy, and generate steam, as shown in FIGS. 5-8 .
  • FIG. 5 for cooling sulfuric acid and recovering energy (which uses an inert coolant; the intermediate acid-fluid cooling step; a second fluid-water cooling step; and an energy recovery step) allows the cooling steps to be performed by shell and tube, plate or spiral heat exchangers and energy recovery, steam generation in the boiler for steam generation.
  • a plant of this type comprises: single or double stage SO 3 absorption tower 1 ; an outlet 2 through which the heated acid circulates after absorption at a temperature between 100 and 240° C.; acid circulation tank 3 and pump 4 .
  • An acid cooling loop 10 is also part of the plant comprising an intermediate acid-fluid heat exchanger 20 ; a second fluid-water heat exchanger 11 , both plate ( FIG. 5 ) or shell and tube ( FIG.
  • a feeding tube 12 that establishes a fluid connection between the pump 4 and the intermediate acid-fluid heat exchanger 20 , through which the heated acid circulates after absorption at a temperature between 100 and 240° C., and a concentration between 98 and 101%; a cooled acid recirculation tubing 13 between the intermediate acid-fluid heat exchanger 20 and single or double stage SO 3 absorption tower 1 through which the cooled acid circulates after absorption at a concentration between 98 and 101%, and a temperature between 100 and 240° C.; inert coolant reuse tubing 21 , which establishes a fluid connection between the intermediate acid-fluid heat exchanger 20 and the second fluid-water heat exchanger 11 , and substantially comprising a tubing, an accumulation vessel and a recirculation pump, through which the heated and cooled fluid circulates.
  • the unit further comprises a cooling and energy recovery, steam generation loop 10 ′ comprising a steam generation boiler 30 ; a feed and return tubing 14 between the second heat exchanger 11 and the boiler 30 ; a tubing 31 for supplying water to the boiler at a pressure between 300 to 3500 kPa; a low or medium pressure (between 300 to 3500 kPa) steam feeding tube 32 , which exits the boiler 30 and can feed any system.
  • the plant further comprises a cold acid feeding tube 15 for temperature adjustment in tower 1 , which feeds acid at a concentration between 98 and 101% and a temperature between 70 and 120° C.
  • the energy recovery system shown in FIG. 5 uses an intermediate acid-coolant plate heat exchanger 20 to cool the hot acid; a second coolant-water heat exchanger 11 to cool the coolant and heat the steam generation medium and a boiler 30 , which uses the water from the second heat exchanger 11 to generate steam.
  • This system offers a number of benefits.
  • the intermediate heat exchanger 20 that cools the hot acid with an inert coolant may operate with the coolant loop at a pressure lower than that of the acid (unlike conventional systems in which the water/steam is at a higher pressure than the acid).
  • any leakage eventually occurring will be from the acid side to the inert coolant side.
  • This leakage may be detected in an expansion tank (not shown) suitably associated with the system wherein the acid separates from the fluid by gravity.
  • a conductivity meter or pH instrument (not shown) can easily detect the leakage. Since there is no acid dilution in the event of a leakage, there is also no accelerated corrosion or hydrogen generation by the formation of hot diluted acid.
  • the heat exchanger 20 of the acid cooling loop used in the present invention can be a high heat transfer plate, shell and tube or spiral heat exchanger and therefore, one may seek to bring the temperature of the coolant closer to that of the acid.
  • Another aspect relating to this invention refers to the fact that because of the contact with the acid, the heat exchanger 20 , tubings and other components of the acid cooling loop associated therewith are made of more noble, and thus more costly materials, to resist this contact.
  • the second heat exchanger (fluid/water) 11 , the boiler 30 and other components associated therewith that have no contact with the acid may be made of a less noble and less expensive material, and, accordingly, particularly the heat exchanger 11 and the boiler 30 can be constructed with a larger area for thermal exchange to recover more energy, which is also an advantage of the system. This is shown in FIG.
  • Another interesting aspect is that in a situation of failure of the boiler 30 , provided there is an option to deviate the heat from the system to a cooling tower, for example, the system may continue to operate at energy recovery temperatures or temperatures of units having no energy recovery.
  • the system shown in FIG. 5 may be built in a simpler way without the second fluid-water heat exchanger 11 , and provide only one acid-fluid heat exchanger 20 ( FIG. 6 ) and the boiler 30 .
  • the coolant itself is used to generate steam. Therefore, the boiler 30 may be built to approach higher temperatures, such as for example 10° C. instead of 20° C. in order to generate a better quality steam (using a fluid that enters the boiler at 235° C. and exits at 215° C.) that enables achieving pressures in the order of up to 1800 kPa, unlike the 1200 kPa that would have been achieved with the conventional arrangement.
  • the system with the second heat exchanger 11 shown in FIG. 5 has the advantage of providing greater safety (even if acid leaks to the coolant loop it still does not expose the boiler to risks because of the intermediate heat exchanger, in this case the second heat exchanger 11 ).
  • the method and equipment of the present invention may provide embodiments contemplating such situation, because the invention provides an intermediate heat exchange which makes it possible to divert part of the water preheated by the water-flowing heat exchanger to a pre-heater for the water from the boiler of the high-pressure system.
  • FIG. 7 shows an embodiment according to which a plant with an intermediate heat exchanger and heating for more than one user is provided.
  • the user is expected to have an acid plant with an approximate capacity of 1000 t/day. From the heat produced in the sulfur furnace and catalytic reactors, this plant should produce approximately 50,000 kg/hr of overheated steam at 4200 kPa and 450° C., a total energy applied to the steam (assuming heating from a boiler water at 100° C. and 4200 kPa) in the order of 40 MW.
  • the plant according to the invention as shown in FIG. 7 comprises an absorption tower assembly consisting of single or double stage SO 3 absorption tower 1 ; its outlet 2 through which the heated acid circulates after absorption at a temperature between 100 and 240° C.; acid circulation tank 3 and pump 4 .
  • the plant further comprises an acid cooling loop 10 comprising an intermediate acid-fluid heat exchanger 20 ; a second fluid-water heat exchanger 11 , both of shell and tube, plate or spiral type; feeding tube 12 that establishes the fluid connection between the pump 4 and the intermediate acid-fluid heat exchanger 20 , through which the heated acid circulates after absorption at a temperature between 100 and 240° C., and a concentration between 97 and 101%; cooled acid recirculation tubing 13 between the intermediate acid-fluid heat exchanger 20 and single or double stage SO 3 absorption tower 1 through which the cooled acid circulates after absorption at a concentration between 97 and 101%, and a temperature between 100 and 240° C.; inert coolant reuse tubing 21 , which establishes a fluid connection between the intermediate acid-fluid heat exchanger 20 and the second fluid-water heat exchanger 11 , and substantially comprising a tubing, an accumulation vessel and recirculation pump, through which, in one line, the heated fluid circulates and in the
  • the plant comprises an energy recovery, steam generation loop, means for pre-heating the water from the boiler of the high pressure system 10 comprising a steam generation boiler 30 , a boiler water pre-heater 50 , a tubing 14 exiting the second heat exchanger 11 and entering the boiler 30 and the boiler water pre-heater 50 , through which the hot water circulates for steam generation; return tubing 14 ′ exiting the boiler 30 and the boiler water pre-heater 50 , which connects with an accumulator vessel 21 , and through which the cooled water circulates after steam generation through tubing 14 ′′, which exits the accumulating vessel 21 and enters the second heat exchanger 11 , through which the cooled water circulates; tubing 31 for supplying water to the boiler at a pressure between 300 and 3500 kPa; 300-1500 kPa low and medium pressure steam tubing 32 exiting the boiler 30 and that can be supplied to any system; feeding 16 and return 16 ′ tubing connected with the pre-heater for the water from the boiler 50 ,
  • the plant further comprises a cold acid feeding tube 15 for temperature adjustment in tower 1 , which feeds acid at a concentration between 97 and 101% and a temperature between 70 and 120° C.
  • This embodiment can only be used to generate medium or low pressure steam, or according to another arrangement, to include more users, such as for example, for heating phosphoric acid, for heating water for industrial or collective use or heating thermal fluids.
  • the sulfuric acid-inert coolant is preferably in the liquid phase at the operating temperatures; it is chemically and thermally stable, not combustible or flammable, has good chemical compatibility with metals and plastics, has low steam pressure at operating temperatures, is nearly insoluble in water and preferably minimally toxic or non-toxic.
  • Said sulfuric acid-inert coolant comprises the family of perfluorocarbons, fluorinated hydrocarbons of chains with more than 5 carbon atoms, for example hydrofluoroethers or perfluoropolyethers or mixtures thereof or the like in their various degrees of polymerization and fluoridation.
  • both can be of the same type, i.e. plate ( FIGS. 5, 7, 8 ) or shell and tubes ( FIG. 2, 5 A) or spiral heat exchanger or the equipment may comprise two different types of heat exchangers working together as shown, for example, in FIG. 8A , all of that for design convenience.
  • the equipment may comprise an assembly or kit to be set up in an existing plant, consisting of a heat exchanger preferably mounted upwards the heat exchanger already existing in the plant such that it comprises the SO 3 absorption tower and first and second heat exchangers according to the present invention.
  • the new heat exchanger may be mounted upwards the heat exchanger already existing in the plant, as desired.
  • the kit further comprises a sulfuric acid-inert coolant load that cooperates with the first heat exchanger sandwiched between the SO 3 absorption tower and the second heat exchanger, using water or other fluid as coolant, according to the invention.
  • the plant comprises the SO 3 absorption tower, the first acid-fluid heat exchanger, preferably part of the kit, and the second inert coolant-water or other fluid heat exchanger, preferably the one existing in the plant.
  • FIGS. 9 to 11 are schemes showing the optional heat exchangers used in the equipment of the invention.
  • FIG. 9 is a scheme showing a coolant-water plate heat exchanger 20 , on one side, comprising an inlet for the heated acid after SO 3 absorption, and an outlet for the cooled acid for SO 3 absorption, and on the opposite side, an outlet for the heated coolant and an inlet for the cooled coolant.
  • FIG. 10 is a scheme showing a coolant-water shell and tube heat exchanger 20 having on the left, an inlet for the heated acid from the absorption of SO 3 , and on the right, an outlet for the heated coolant and an outlet for the cooled acid for absorption of SO 3 and an inlet for the cooled coolant.
  • FIG. 11 is a scheme showing a coolant-water spiral heat exchanger having on one side an inlet for the heated acid from the absorption of SO 3 , and above an outlet for cooled acid for absorption of SO 3 , on the opposite side, an outlet for heated coolant and on the upper side, an inlet for the cooled coolant.

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BR1020160036909 2016-02-22
BR102016003690-9A BR102016003690B1 (pt) 2016-02-22 2016-02-22 Método e equipamento para resfriar ácido sulfúrico
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PCT/BR2016/050287 WO2017143416A1 (pt) 2016-02-22 2016-11-07 Método e equipamento para resfriar ácido sulfúrico

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EP4043820A4 (en) * 2019-09-27 2023-10-25 Clark Solutions LLC SAFETY BUFFERED MULTI-LUID HEAT EXCHANGER AND SAFETY BUFFERED MULTI-LUID HEAT EXCHANGE METHOD
CN112604541B (zh) * 2020-11-25 2023-02-07 河北超威电源有限公司 一种蓄电池用胶体酸的制备方法及专用制备装置
CN113521966A (zh) * 2021-07-26 2021-10-22 浙江大学 基于传质-反应调控的分区多级循环co2捕集浓缩方法
CN116101982B (zh) * 2023-01-09 2024-06-14 江苏吉华化工有限公司 一种硫磺制酸系统及制酸方法

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WO1991014651A1 (en) 1990-03-23 1991-10-03 Monsanto Company Methods for recovering high grade process energy from a contact sulfuric acid process
US5118490A (en) 1989-06-21 1992-06-02 Monsanto Company Absorption of wet conversion gas
DE102010006541A1 (de) 2010-02-01 2011-09-29 Outotec Oyj Verfahren und Anlage zur Abkühlung von Säure
DE202015106813U1 (de) 2014-12-19 2016-01-20 Outotec (Finland) Oy Anlage zur energieeffizienteren Herstellung von Schwefelsäure

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US5118490A (en) 1989-06-21 1992-06-02 Monsanto Company Absorption of wet conversion gas
WO1991014651A1 (en) 1990-03-23 1991-10-03 Monsanto Company Methods for recovering high grade process energy from a contact sulfuric acid process
DE102010006541A1 (de) 2010-02-01 2011-09-29 Outotec Oyj Verfahren und Anlage zur Abkühlung von Säure
US20130000869A1 (en) * 2010-02-01 2013-01-03 Outotec Oyj Process and plant for cooling sulfuric acid
DE202015106813U1 (de) 2014-12-19 2016-01-20 Outotec (Finland) Oy Anlage zur energieeffizienteren Herstellung von Schwefelsäure

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